Unfiled tax returns are a serious offense in the eyes of the IRS, and can lead to mounting debt as back taxes and fines pile up. The IRS will not stop the collections process until all unfiled tax returns have been filed, and you have paid back all money due. If you continue to fail to file your taxes, the IRS will place a levy on your wages.
The IRS knows you haven't filed
If you have unfiled tax returns, the best way to stay out of trouble with the IRS is to immediately file your back taxes. Think that the IRS doesn't notice your unfiled tax returns? Think again. Even if it's been years since the unfiled taxes, the IRS can notify you at any time that they know and are ready to aggressively pursue back tax payments.
File for yourself before the IRS can file for you
When you fail to act before the IRS does, they will file a substitute for return (SFR) for you. An SFR is based on the IRS's best guess of your income, and will have penalties and fines tacked onto your tax bill. There is no chance for deductions on an SFR, so it makes sense to file your back taxes before the IRS has a chance to file an SFR for you.